It's an ethnic slur for a black person, seemingly common for Italian-Americans. As User says, it comes from the Southern Italian mulignana, meaning eggplant, though most sources listed it as Sicilian.
Tony Soprano: What I mean is we're Italian?
Noah Tannenbaum: Oh, my dad is Jewish and my mother's family is African American.
Tony Soprano: Tanenbaum. Right. But on your application to Columbia, you didn't check Jewish did you?
Noah Tannenbaum: No. They can't ask about religious affiliation.
Tony Soprano: Oh, right...right...o' course. What'd you check?
Noah Tannenbaum: African American.
Tony Soprano: So we do understand each other; you're a ditsoon.
Noah Tannenbaum: Excuse me?
Tony Soprano: Charcoal Briquette...a mulignan.
Noah Tannenbaum: What's your problem?
Tony Soprano: I think you know what my problem is. You see your little friend up there. She didn't do you any favors bringing you into this house. Now I dunno what the fuck she was thinkin', we'll get to that later. See I got business associates who are black and they don't want my son with their daughters and I don't want their sons with mine.
Noah Tannenbaum: Fuck you!
Tony Soprano: See, that's the kind o' thing I'm hopin' to avoid. So when my little girl comes down the stairs, you're gonna say how nice it was to meet me, then you're gonna go drop her off at school and you're gonna say Goodbye.
by goodfella68 April 4, 2018
Get the Mulignan mug.
The origin of the AE word "mulignan" is not directly linked to the italian word "melanzana" (eggplant).
"Melanzana" is the standard italian word for "eggplant" but every region and even every town in the same region has its own dialect form(s).
I wanted to go further and made a little research and here is what I found.

"Melanzana" comes from the low-latin "melangolus" or"merongolus" from the arab "bâdindgiân". It is possible to find the same name in old french "mélangène" even if the current french word for "eggplant" is "aubergine".

As you can see from these examples, all the words are similar. We can assume that the AE word "mulignan"
was imported to the US by italian immigrants coming from a southern region but nothing tells us if it was Sicily or Napoli.

I hope this helped.
According to the different regions, one can find these forms of the italian word "melanzana":

"buligname" Abruzzo
"malangiana" Calabria
"marangiana" Puglia
"marignanu" Umbria
"melangiàne" Puglia
"mulingiana", "milinciana" Sicilia
"mulignana" Napoli
by orros March 25, 2010
Get the Mulignan mug.
A term derived from the Italian melenzane meaning "eggplant." It often is used as a derogatory term to describe black people. The term is of Neapolitan origin not Sicilian origin as some on here have stated. The Sicilian word sounds more like "milinciana" or mill-in-chyan-ah.
Junior Soprano : "Heroin back in the fifties it was raining cash with that shit. DiMaggio and his crew never saw a dime... Turns out, the cock sucker was making a fortune working with the mulignan."
by GazzNGabb July 9, 2021
Get the mulignan mug.
-a racially offensive term for a black person (from Italian melanzana, which is an eggplant.)NOTE: there are hundreds of phonetic spellings out there; however, this is the ONLY correct Italian spelling of this word.
He was accused of being a racist when he called the black man a mulignan at the bus stop.
by weave March 19, 2003
Get the mulignan mug.
"Meadow's still goin' out wit dat mulignan." -Tony Soprano
by Tony Soprano February 9, 2004
Get the mulignan mug.
This is the term for "African Americans" used by most Italian-American males, myself included. I grew up hearing my father and grandfather using it all of the time, so it's only natural.
Newark used to be a nice place, but now there are too many mulignans.
by Danny boy September 2, 2004
Get the mulignan mug.
(n) (1) a variation of the Italian word for eggplant. (2) a person of direct African descent (a black person). Actually, this term has nothing to do with slavery, because Italians rarely if ever had black slaves, and most Italians were in favor of giving rights to blacks while the whites up in Northern Europe and America were still using blacks for labor and slave trades. The real origin of this slang word is unknown, but it is not as popular among Italians as the movies and white people suggest. Most people now that use the word "mooley" are white, not Italian.
Some Angry Guy: Yo, what's up with all these mulignans in my hood? Get outta here, ya mooley.

Some Guy With Sense: What the hell are you talking about? Stop saying "mooley", you asshole. You're not even Italian, you're white. And even if you were Italian, it be even more ignorant to be rascist towards blacks, considering Italians aren't white and are closely related to blacks. Italians and blacks should be brothers.
by New Jack Swing January 6, 2006
Get the mulignan mug.